A former FBI agent charged with lying on the witness stand during the 2013 trial of former Boston mob boss James "Whitey" Bulger is expected in court on Monday and will likely plead guilty to at least some charges.

The first witness called by Bulger's attorneys, Robert Fitzpatrick made a variety of statements on the witness stand, including that he concluded that the Federal Bureau of Investigation should not be working with Bulger as an informant because when he looked into his eyes he "couldn't see his soul."

Fitzpatrick also said that he had been the first FBI agent on the scene of civil rights activist Martin Luther King Jr.'s assassination in 1968 and that he had later been sent to Boston on a special assignment to clean up "major problems" in that office.

Some of the assertions were so striking that Bulger's attorney asked Fitzpatrick directly at the time if he was lying.

The trial cast a harsh light on the corrupt relationship between the Irish-American gangster and FBI agents who shared Bulger's heritage and turned a blind eye to his gang's murder and mayhem in exchange for information it could use against the Italian-American Mafia.

Fitzpatrick was arrested last year and charged with 12 criminal counts of perjury and obstruction of justice, over several statements made on the witness stand that prosecutors contend were lies.

Fitzpatrick, who served in the FBI from 1965 through 1986, pleaded not guilty in his first court appearance on the perjury charges. Court filings show that a hearing has been set for Monday for him to change his plea; the filing does not make clear which of the charges he plans to plead guilty to.

His attorney declined in an email to offer further details on Fitzpatrick's plans.

Bulger, 86, has denied serving as an informant, insisting he paid agents for tips but provided none of his own.

He fled the city in 1995 on a tip from an FBI handler that arrest was imminent, and was a fugitive for 16 years, most of them atop the FBI's "Ten Most Wanted" list. Agents caught up with him in an apartment in Santa Monica, California, in 2011.

He is serving a life sentence after being convicted of committing or ordering 11 murders while head of the Winter Hill gang in the 1970s and '80s.

The 2015 movie "Black Mass" told the story of Bulger's rise to power and eventual arrest.